1.STRUCTURE AND BONDING Prepared by Janadi Gonzalez-Lord

2. TABLE OF CONTENTS Prepared by JGL 8/21/2009 Syllabus requirements Covalent bonding Review: atoms and the Covalent nomenclature periodic table Properties of covalent Elements and bonding compounds Representing ions and Metallic bonding molecules Properties of metallic Ion formationcompounds CATION formation Allotropes ANION formation Atomic radius Ionic Bond formation Electronegativity Representing ionic bonding Thermodynamics of ion Ionic nomenclature formation Properties of ionic compounds 2 3. Prepared by JGL 8/21/2009 SYLLABUS REQUIREMENTS 3 BONDING 4. SYLLABUS REQUIREMENTS IONIC BONDINGPrepared by JGL8/21/2009 The students should be able to : state that atoms like to achieve a stable state by electron gain orloss recognize the tendency for loss or gain based on the electronicconfiguration or the position in the periodic table ( for the first twentyelements ) 4 state that ions are formed by the gain or loss of the electrons 5. SYLLABUS REQUIREMENTS - BONDING Prepared by JGL 8/21/2009 The students should be able to : Define anion and cation Recognize that charge is equal to protons minus electrons Identify the number of protons , electrons in and the electronicconfiguration of an ion . ( first twenty elements only ) Write symbols for ions and molecules Identify the two main types of bonding as ionic / electrovalent and 5 covalent 6. SYLLABUS REQUIREMENTS - BONDING Prepared by JGL 8/21/2009 The students should be able to :Explain metallic bondingState the differences between ionic, covalent and metallic bondingIdentify the types of bonding present in substances based on theirpropertiesPredict the properties of substances based on the bonding presentDraw diagrams to illustrate the types of bondingPredict the types of bonding between elements6 7. Prepared by JGL 8/21/2009 SYLLABUS REQUIREMENTS 7 STRUCTURE 8. SYLLABUS REQUIREMENTS - STRUCTUREPrepared by JGL8/21/2009 Students should be able to1.Define and give examples of ionic crystals, simplemolecular structures and giant molecular crystals2.Explain the term allotropy3.Relate structures of sodium chloride, diamond andgraphite to their properties8 4.Distinguish between ionic and molecular solids 9. Prepared by JGL 8/21/2009 REVIEW: ATOMS AND THE PERIODIC TABLE 9 10. Prepared by JGL 8/21/2009 10 11. These columns are known asGROUPS are also known asGROUPSFAMILIES GROUPS IN THE PERIODIC TABLE10 11 12 13 14 15 16 17 1812 34 5 6 7 8 9There are 18GROUPS Prepared by JGL 11 8/21/2009 12. Elements within a group have similar All have the same number ofphysical and chemical properties electrons in their outermost or valence shells Example Na (2,8,1) and K (2,8,8,1) are both in Group 1Prepared by JGL128/21/2009 13. The rows are known as PERIODS. There are 9 periods MAIN PERIODS IN PERIODIC TABLE1 2 3 4 5 6 7 89 Prepared by JGL138/21/2009 14. Prepared by JGL 8/21/2009ELEMENTS AND BONDING 14 Introduction to ionic, covalent and metallic bonding 15. 3/30/2010 Prepared by JGLPURE AND IMPURE SUBSTANCES 15 A review 16. 3/30/2010 Prepared by JGL Matter can be sub-divided into PURE and IMPURE SUBSTANCES or MIXTURES.PURE substances can be sub-divided into ELEMENTS and COMPOUNDS16 IMPURE substances or MIXTURES can be sub-divided into HOMOGENOUS and HETEROGENOUS 17. 3/30/2010Can be separated intoPrepared by JGLCan be Can be separated separatedinto into 17 Source: www.mghs.sa.edu.au/Internet/Faculties/Science/Year10/Pics/elementsAndCompounds.gif 18. 3/30/2010 ELEMENTS VERSUS COMPOUNDS An element....A compound...... 18 consists of only one kind consists of atoms of two or more different elements bound of atom together, cannot be broken down can be broken down into a into a simpler type ofsimpler type of matter (elements) by chemical means matter by either physical (but not by physical means), or chemical means has properties that are different can exist as either atoms from its component elements, (e.g. argon) or molecules always contains the same ratio of its component atomsPrep (e.g., nitrogen). aredby JGL 19. 19Prepared by JGL3/30/2010 AN ELEMENTConsists of only one kind of atomAr Arcan exist as either atoms (e.g.argon) or molecules (e.g., nitrogen). NN cannot be broken down into asimpler type of matter by eitherphysical or chemical meansNN If you try to break apart an atom ormolecule, you get an ATOMICBOMB 20. 20 Prepared by JGL 3/30/2010 H H A COMPOUND O consists of atoms of two or more different elements bound togetheralways contains the same ratio of its component atoms H H O Water (formula H2O)H H O O H H For every water molecule, there are 2 O Hydrogen atoms for every 1 Oxygen atom H H has properties that are different from its O component elements H H O For example, hydrogen and oxygen are gases but water is a liquid 21. 21Prepared by JGL3/30/2010 EXAMPLES OF ELEMENTS AND COMPOUNDSElements Compounds Source: www.physicalgeography.net/fundamentals/images/compounds_molecules.jpg 22. WHY DO COMPOUNDS FORM IN THE FIRST PLACE?Prepared by JGL8/21/2009 Scientists found that elements in Group 8 were very non- reactive. They also noticed that those in Groups 1,2,6 and 7 were extremely reactive. They also noticed that metallic substances had several properties that were very different from other elements. They could not at first understand why. Eventually they discovered that it had to do with ELECTRON CONFIGURATIONSandSTABILITY22 23. ELECTRON CONFIGURATION AND STABILITY Prepared by JGL 8/21/2009 Scientists research showed that in compounds, elements willcombine so that the valence or outermost electrons will have the same electronconfiguration as the nearestnoble gas 23 (in Group 8) 24. HOW CAN ELEMENTS COMBINE TO ACHIEVE THIS?An element can gain electrons from the Prepared by JGLelement it combines with to have the same 8/21/2009electron configuration as the nearest noblegas. Once an atom gains one or moreelectrons, it becomes a negatively charged particle known as an ANION An element can lose electrons to another An element can share element to have thevalence electrons withsame electron another element to configuration as thenearest noble gas.have the sameOnce an atom loses one Thereelectron configurationare threeas the nearest noble or more electrons, it gas.forms a positively(3) wayscharged particle knownas a CATION. 24 25. Prepared by JGL YOU MAY WELL8/21/2009 BE ASKINGWHAT DOESTHIS MEAN?25 26. Prepared by JGL LETS TAKE A LOOK 8/21/2009 AT SOME EXAMPLES TO UNDERSTAND THIS CONCEPT MOREFULLY26 27. Sodiums atomic numberNeons atomic number is is Z=11. Its electronZ=10. Its electron Lets take sodium as an exampleconfiguration is thereforeconfiguration is 2,8. It is 2,8,1 the nearest noble gas to sodium. Sodium will combine with another element so that itcan change its electron configuration from 2,8,1 to 2,8. To do this, it must lose 1 electron and give it to Prepared by JGL the element with which it combines. 278/21/2009 28. Chlorines atomic number Argons atomic number is Z=17. Its electronis Z=18. Its electron Lets take chlorine as an exampleconfiguration is therefore configuration is 2,8,8. It 2,8,7 is the nearest noble gas to chlorine. Chlorine will combine with another element so that itcan change its electron configuration from 2,8,7 to 2,8,8. To do this, it must gain 1 electron from the Prepared by JGLelement with which it combines. 288/21/2009 29. Prepared by JGL8/21/2009SODIUM AND CHLORINE UNDERGO WHAT IS KNOWN ASIONIC BONDING.29 30. IN IONIC BONDINGPrepared by JGL8/21/2009 An element can lose or gain electrons to another element within the same compound to have the same electron configuration as the nearest noble gas. These are known as IONS. The electrostatic attraction between these ions is known as an IONIC bond 30 31. In order to form IONIC BONDING OF SODIUM CHLORIDEthe compoundsodiumchloride, there arePrepared by JGLthree (3) steps.8/21/2009First, the sodiumatom loses oneelectron to form apositive sodiumion. (cation) Then the chlorineatom accepts theelectron from thesodium atom toform a negativechloride ion(anion). Then the sodiumcation andchloride anionbecome attractedto each due totheir differentcharges, formingan ionic bond31 Source: www.revisionworld.co.uk 32. Carbons atomic number Neons atomic number isis Z=6. Its electron Z=10. Its electron Lets take carbon as an exampleconfiguration is therefore configuration is 2,8. It is2,4 the nearest noble gas tocarbon. Carbon will combine with another element so that it can changeits electron configuration from 2,4 to 2,8. To do this, it must share 4 electrons with the element with which it combines as it is equally difficult to lose or gain four electrons. Prepared by JGL328/21/2009 33. COVALENT BONDING Prepared by JGL 8/21/2009 An element can share valence electrons with another element to have the same electron configuration as the nearest noble gas. This sharing of valence electrons is known as COVALENT bonding. 33 34. Covalent bondis the sharing of two COVALENT BONDING Prepared by JGL electronsbetween the 2 8/21/2009 atoms Two hydrogen atoms can share their valence electrons to attain the same electron configuration of the nearest Noble gas configuration, Helium 34 35. The valence (outermost)electrons are loosely held by METALLIC BONDINGPrepared by JGL the metal ions, so much sothat they move away from8/21/2009The electrons are free to move fromthe atom to form a positively one positively charged ION to the charged ION.next (i.e. They are DELOCALISED) However, metals like in covalentand are shared (just behavebonding among the various metallic differently. positively charged ionsMetallic bonding is similar toboth covalent and ionicbonding The number of electrons = the number of protons. Source: www.daviddarling.info/images/metallic_bond.jpgThe metal is therefore35Syllabus requirement met: electrically NEUTRAL Explain metallic bonding 36. IN SUMMARYPrepared by JGL8/21/2009Ionic bonding 3 typesof bondingMetallic Covalentbondingbonding36 37. COMPARE AND CONTRAST TYPES OF BONDING Prepared by JGL SimilaritiesDifferences 8/21/2009 Metallic and ionic Covalent bonding shares bonding involveelectrons rather than electrostatic attractionshaving electrostatic between positive and charges. negatively charged particles. Ionic bonding will form Metallic bonding sharescompounds whereas electrons among the ions covalent bonding can in a similar manner to form a compound or how electrons are shared element and metallic in covalent bonding. bonding is strictly foundin elements Syllabus requirement met: 37 State the differences between ionic, covalent and metallic bonding 38. Prepared by JGL 8/21/2009REPRESENTING IONS ANDMOLECULES 38 Ionic notation, chemical formulae 39. Mass Number RECALL BASIC ATOMIC NOTATION Prepared by JGL= number of protons + 8/21/2009 number of neutronsA Atomic number= Number ofprotons Z X Element symbol 39 40. Ionic chargePrepared by JGL WE CAN ALSO= number of protons - number of electrons8/21/2009 DISPLAY OTHER INFORMATION n+/-Number of atomsX m of element X in molecule or ionElement symbol40 41. Mass Number Ionic charge ALTOGETHER of protons + = number Prepared by JGL = number of protons -number of neutronsnumber of electrons 8/21/2009A n+/-Atomic X numberNumber of atoms = Number ofof element X in protonsmolecule or ion Z m Element symbol 41 42. Mass Number EXAMPLE: SODIUM IONPrepared by JGL8/21/2009 Element symbol Na23 1+ Ionic charge Charge = +1Atomic Number Z = 11 11 Na Mass number A = 23Element symbolAtomic number Z42 43. Mass Number EXAMPLE: HYDROGEN MOLECULE Prepared by JGLNumber of 8/21/2009 Element symbol H2 atoms of hydrogen in aCharge = 0Atomic Number Z = 1 Hmolecule of hydrogen1 2 Mass number A = 2 Element symbolNumber of HydrogenAtomic number Zatoms in a molecule ofhydrogen = 243 44. Prepared by JGL 8/21/2009 ION FORMATION 44 45. IONS DEFINEDPrepared by JGL8/21/2009An ion is an atom or molecule where the total number ofelectrons is not equal to thetotal number of protons, givingit a net positive or negativeelectrical charge.Syllabus objective met: 45State that ions are formed by the gain orloss of the electrons 46. REVIEW ELECTRON CONFIGURATIONS Prepared by JGL 8/21/2009 What is an electron configuration? Definition: Electron configuration is the arrangement of electrons in an atom, molecule or other body. How do we represent electron configurations? By using Bohr-Rutherford diagrams Or electron configuration notation 2,8,111 p10 n46 47. REMEMBER CONTRAST MEANS LOOK AT THE DIFFERENCESLETS CONTRAST F AND NE Prepared by JGL 8/21/2009 FluorineNeon Element symbol F Element symbol Ne Group 17 Group 18 Atomic Number Z = 9 Atomic Number Z = 10 Mass number A = 19 Mass number A = 20 Electron configuration: 2,7 Electron configuration: 2,8 Bohr-Rutherford diagram Bohr-Rutherford diagram9p10 p10 n10 n47 48. LETS CONTRAST NA & NE Prepared by JGL 8/21/2009 SodiumNeon Element symbol Na Element symbol Ne Group 1 Group 18 Atomic Number Z = 11 Atomic Number Z = 10 Mass number A = 23 Mass number A = 20 Electron configuration: 2,8,1 Electron configuration: 2,8 Bohr-Rutherford diagram Bohr-Rutherford diagram 11 p 10 p 12 n 10 n48 49. Remember Compare meansLook atCOMPARE AND CONTRAST ALL 3 ELEMENTSPrepared by JGL8/21/2009 Similarities Differences F and Ne have the Different atomic numbers(Z) and therefore protons same number of Different mass numbers (A) electron shellsand therefore differentneutrons Scientists found that when F needs to gain 1 electronelements from Group 1 andto have the same number of Group 7 combined, they lost orelectrons as Ne gained an electron to have thesame number of electrons as Na needs to lose 1 electron the nearest Noble Gas. to have the same number ofelectrons as Ne i.e. F and Na form ions that Syllabus requirement met: 49 are ISO-ELECTRONIC withstate that atoms like to achieve a stable Ne state by electron gain or loss 50. IN GENERALPrepared by JGL Groups 1, 2 and 3 Groups 15, 16 and 178/21/2009 To become ISO-To become ISO-ELECTRONICELECTRONIC with thewith the nearest Noble Gasnearest Noble Gas (either(either within the same Periodwithin the same Period or theor the Period just above)Period just above)1. Group 15 elements gain 3 e- 1.Group 1 elements lose 1 e- 2. Group 16 elements gain 2 e- 2.Group 2 elements lose 2 e- 3. Group 17 elements gain 1 e- 3.Group 3 elements lose 3 e-This only happens when combining or reacting with This only happens when another element(s) fromcombining or reacting with Groups 1,2 or 3another element(s) fromGroups 15,16 or 1750 51. Prepared by JGL 8/21/2009 CATION FORMATION51 52. CATION FORMATION Prepared by JGL 8/21/2009 Lets take an unknownLets assume that this element X that has anatom of X loses 1 atomic number Z = 10 electron. and a electrical charge of zero. Now# of protons (p) = 10 For an atom of X,# of electrons (e) = 10 -1 = 9 # of protons (p) = 10Charge on ion = 10 9 = +1 # of electrons (e)= 10 Charge of atoms = 10 10 =052 53. IF WE THINK OF IT LIKE AN EQUATION, Prepared by JGL 8/21/2009For an atom of XFor an positive ion of X+ 10 p+ 10 p- 10 e- 9e 0+1 In general, a positive ion formed by the loss of one or more electrons is known as a CATION. Syllabus objectives met: Define cation Recognize that charge is equal to protons minus electrons 53 54. Group 1 elements have 1 This is the same electron valence (outermost) electron configuration as Ne, the noble gas just above Na (Period 2, THEPERIODIC TABLE If Na loses 1 electron, its electron configuration Na ion and Ne Group 8). i.e.becomes (2,8)are ISO-ELECTRONIC If K loses 1electron, its electronconfigurationThis is the same electron Example Naconfiguration as Ar, the noblebecomes (2,8,8) (2,8,1) and gas just above K (Period K (2,8,8,1) 2, Group 8). i.e. K ion and Ar are both inare ISO-ELECTRONIC Group 1Prepared by JGL 54 8/21/2009 55. CATION FORMEDPrepared by JGL8/21/2009 If Na loses 1 p = +11 electron, its electrone-= - 10 configuration moves Charge= +1 from (2,8,1) to (2,8). Since the number of protons remains the It therefore becomes a same (p=11) but thecation with an electrical number of electronscharge of +1 change (e- = 10), it is no longer electrically neutral55 56. CATION FORMED Prepared by JGL 8/21/2009 If K loses 1 electron, its p = +19 electron configuration e-= - 18 moves from (2,8,8,1) toCharge= +1 (2,8,8). Since the number of protons remains theIt therefore becomes a same (p=19) but the cation with an electrical number of electrons charge of +1 change (e- = 18), it is no longer electrically neutral 56 57. IN GENERALPrepared by JGL8/21/2009Li, Na and K are in groupAll group 11 elementsSo lose 1 e- to Li loses 1 e- to form Li+form aNa loses 1 e- to form Na+cation withan electrical K loses 1 e- to form K+ charge of +157 58. Group 2 elements have 2This is the same electronvalence (outermost) electronsconfiguration as Ne, the noble gas just above Mg (PeriodTHE PERIODIC TABLE If Mg loses 2 electrons, its electron configuration 2, Group 8). i.e. Mg ion andbecomes (2,8) Ne are ISO-ELECTRONIC If Ca loses 2electrons, its Example Mg electronThis is the same electron (2,8,2) andconfiguration configuration as Ar, the noble Ca(2,8,8,2) becomes (2,8,8)gas just above Ca (Period are both in 2, Group 8). i.e. Ca ion and Group 2 Ar are ISO-ELECTRONIC Prepared by JGL58 8/21/2009 59. CATION FORMEDPrepared by JGL8/21/2009 If Mg loses 2 p = +12 electrons, its electron e-= - 10 configuration moves Charge= +2 from (2,8,2) to (2,8). Since the number of protons remains the It therefore becomes a same (p=12) but thecation with an electrical number of electronscharge of +2 change (e- = 10), it is no longer electrically neutral59 60. CATION FORMEDPrepared by JGL8/21/2009 If Ca loses 2 p = +20 electrons, its electron e-= - 18 configuration moves Charge= +2 from (2,8,8,2) to (2,8,8). Since the number of It therefore becomes a protons remains thecation with an electrical same (p=20) but thecharge of +2 number of electrons change (e- = 18), it is no longer electrically neutral60 61. IN GENERAL Prepared by JGL 8/21/2009 Be, Mg and Ca are inAll group 2 group 2 elementsSo lose 2 e- to Be loses 2 e- to form Be2+form aMg loses 2 e- to form Mg2+cation withan electrical Ca loses 2 e- to form Ca2+ charge of +2 61 62. Group 13 elements have 3This is the same electronvalence (outermost) electronsconfiguration as He, the noblegas just above B (Period THE PERIODIC TABLE1, Group 8). i.e. B ion and HeIf B loses 3 electrons, its electron configuration becomes (2) are ISO-ELECTRONIC If Al loses 3electrons, itsExample electronB(2,3) andconfigurationThis is the same electronAl(2,8,3) arebecomes (2,8) configuration as Ne, theboth in noble gas just above AlGroup 3 (Period 2, Group 8). i.e. Alion and Ar are ISO- ELECTRONIC Syllabus requirements met: Recognize the tendency for loss of electrons based on the electronic configuration or the position in the periodic table ( for metals)Prepared by JGL 628/21/2009 63. CATION FORMEDPrepared by JGL8/21/2009 If B loses 2 electrons, p = +5 its electrone-=-2 configuration moves Charge=+3 from (2,3) to (2). Since the number of protons remains the It therefore becomes a same (p=5) but the cation with an electrical number of electronscharge of +3 change (e- = 2), it is no longer electrically neutral63 64. CATION FORMEDPrepared by JGL8/21/2009 If Al loses 3 p = +13 electrons, its electron e-= - 10 configuration moves Charge= +3 from (2,8,3) to (2,8). Since the number of protons remains the It therefore becomes a same (p=13) but thecation with an electrical number of electronscharge of +3 change (e- = 10), it is no longer electrically neutral64 65. IN GENERAL Prepared by JGL 8/21/2009 B and Al are in group 13All group 13 elements SoB loses 3 e- to form B3+ lose 3 e- toform aAl loses 3 e- to form Al3+ cation withan electricalcharge of +3 65 66. RECALL: METALSGroup 1 to 13 and periods 8 and 9 are METALS Metals 10 11 12 13 141 2 34 5 67 8 9MetalsPrepared by JGL668/21/2009 67. RECALL Prepared by JGL 8/21/2009 Basic Math equation Ionic half-equationFor the basic mathematicalWe could write equation: Na 1e- Na+ X3=0 If we treat the as In order to solve for x , you =, we could take across take the number 3 across to the 1e- to the RHS and the right hand side (RHS) of the equation and change change the sign as well the sign.Na Na+ +1e- 67X = +3 68. SO FOR GROUP 1 ELEMENTSPrepared by JGL8/21/2009 Statement Ionic half-equationLi loses 1 e- to form Li+ Or Li 1e- Li+Li Li+ +1e-Na loses 1 e- to form Na+Or Na 1e- Na+ Na Na+ +1e-K loses 1 e- to form K+K K+ +1e- OrK 1e- K+68 69. SO FOR GROUP 2 ELEMENTS Prepared by JGL 8/21/2009 StatementIonic half-equationBe loses 2 e- to form Be2+ OrBe 2e- Be2+ Be Be2+ + 2e-Mg loses 2 e- to form Mg2+ OrMg 2e- Mg2+ Mg Mg2+ +2e-Ca loses 2 e- to form Ca2+ Ca Ca2+ +2e-Or Ca 1e- Ca2+ 69 70. SO FOR GROUP 13 ELEMENTSPrepared by JGL8/21/2009 StatementIonic half-equationB loses 3 e- to form B3+ OrB 3e- B3+B B3+ + 3e-Al loses 3 e- to form Al3+ Or Al 3e- Al3+ Al Al3+ + 3e-70 71. IN GENERAL METALS LOSE ELECTRONS TOPrepared by JGL FORM POSITIVE IONS8/21/2009 Group 1 metals form mono-positive cations For example In words: sodium loses 1 electron to form sodium cation In chemical equation form:Na Na+ + 1e- Group 2 metals form di-positive cations. For example In words: Magnesium loses 2 electrons to form magnesium cation In chemical equation form:Mg Mg2+ + 2e- Group 13 metals form tri-positive cations In words: Aluminium loses 3 electrons to form aluminium cation In chemical equation form:Al Al3+ + 3e-71 72. WHAT ABOUT TRANSITION METALS?Prepared by JGL8/21/2009 Recall: Transition metals are Groups 3 to 12 They also form cations However, they ccan form cations with multiple valences. For e In chemical equation form: Na Na+ + 1e- Group 2 metals form di-positive cations. For example In words: Magnesium loses 2 electrons to form magnesium cation In chemical equation form: Mg Mg2+ + 2e- Group 13 metals form tri-positive cations In words: Aluminium loses 3 electrons to form aluminium cation72 In chemical equation form: Al Al3+ + 3e- 73. SUMMARY CATION FORMATION Prepared by JGL 8/21/2009 Cations are positiveions. The atoms loseelectrons to achieve the They are formed by losselectron configuration of of electrons. the nearest noble gasMetals (Groups 1 to 13)form cations 73 74. Prepared by JGL 8/21/2009 ANION FORMATION 74 75. This is the same electron Group 15 elements have 5configuration as Ne, the noblevalence (outermost) electrons gas in the same period as NTHE PERIODIC TABLE(Period 3, Group 8). i.e. N ion If N gains 3 electrons, its electron configurationand Ne are ISO-becomes (2,8) ELECTRONICIf P gains 3 electrons, its Example electron This is the same electron N(2,5) andconfiguration configuration as Ar, the P(2,8,5) are becomes (2,8,8) noble gas in the same period both inas P (Period 3, Group 8). i.e. Group 5P ion and Ar are ISO-ELECTRONICPrepared by JGL 758/21/2009 76. This is the same electron Group 16 elements have 6configuration as Ne, the noblevalence (outermost) electronsgas in the same period as O THE PERIODIC TABLE(Period 2, Group 8). i.e. O ion If O gains 2 electrons, its electron configuration and Ne are ISO-becomes (2,8)ELECTRONICIf S gains 2 electrons, its Example electron O(2,6) andconfigurationThis is the same electron S(2,8,6) are becomes (2,8,8) configuration as Ar, the noble both ingas in the same period as S Group 6 (Period 3, Group 8). i.e. S ion and Ar are ISO-ELECTRONIC Prepared by JGL 768/21/2009 77. This is the same electronGroup 17 elements have 7 configuration as Ne, the noble valence (outermost) electronsgas in the same period as O T HE PERIODIC TABLE (Period 2, Group 8). i.e. F ion If F gains 1 electron, its electron configurationand Ne are ISO-becomes (2,8)ELECTRONICIf Cl gains 1electron, its electronExampleconfigurationF(2,7) and This is the same electronbecomes (2,8,8)Cl (2,8,7) configuration as Ar, the nobleare both ingas in the same period as ClGroup 7 (Period 3, Group 8). i.e. Clion and Ar are ISO- ELECTRONIC Syllabus requirements met: Recognize the tendency for loss or gain based on the electronic configuration or the position in the periodic table ( for the first twenty elements)Prepared by JGL778/21/2009 78. RECALL: NON-METALS Groups 14 to 18 are Non-metals Non- Metals14 15 16 17 18 Atoms and The Periodic Table Prepared78 by JGL3/30/2010 79. IN GENERAL, NON-METALS GAINPrepared by JGL ELECTRONS TO FORM NEGATIVE IONS8/21/2009 Group 15 non-metals form tri-negative anions For example In words: nitrogen gains 3 electrons to form nitride anion In chemical equation form:N + 3e- N3-Group 16 non-metals form di-negative anions For example In words: oxygen gains 2 electrons to form oxide anion In chemical equation form: O + 2e- O2-Group 17 non-metals form mono-negative anions For example In words: fluorine gains 1 electron to form fluoride anion In chemical equation form:F + 1e- F-79 80. ANION FORMATIONPrepared by JGL8/21/2009 Lets take an unknownLets assume that this element Y that has anatom of Y gains 2 atomic number Z = 11 electron. and a electrical charge of zero. Now# of protons (p) = 11 For an atom of Y,# of electrons (e) = 11 +2 = 13 # of protons (p) = 11Charge on ion = 11 13 = -2 # of electrons (e)= 11 Charge of atoms = 11 11 =0 80 81. IF WE THINK OF IT LIKE AN EQUATION,Prepared by JGL8/21/2009 For an atom of Y For a negative ion of Y+ 11 p+ 11 p- 11 e- 13 e 0 -2 In general, a negative ion formed by the gain of one ormore electrons is known as a ANION. Syllabus objectives met: Define anion Recognize that charge is equal to protons minus electrons81 State that ions are formed by the gain or loss of the electrons 82. SUMMARY ANION FORMATIONPrepared by JGL8/21/2009 Anions are negativeionsNon-metals loseelectrons to attain theNon-metals gainelectron configuration ofelectrons to form anions the nearest noble gas.Non-metals areelements in Groups 14to 18 82 83. Prepared by JGL 8/21/2009 IONIC BOND FORMATION83 84. RECALL... Prepared by JGL 8/21/2009 Cations Anions Are positive ions Are negative ions Are formed from metals Are formed from non- (groups 1-13) metals (groups 14-18) Are formed when Are formed when non- metals lose electrons metals gain electronsThe ionic bondattain the electron to attain the electronto is the configuration of theconfiguration of the electrostatic attraction gas nearest noble gas nearest noble between anion and cation84 85. HOW TO RECOGNIZE AN IONIC COMPOUNDPrepared by JGL8/21/2009 Ionic MetalNon-metal compound85 86. Prepared by JGL MetalsNon- 8/21/2009Group 1 to 13 are METALS Metals Groups 14 to 18 are Non- Metal Non-metalmetals Ionic compound Periods 8 and 9 are METALS Metals86 87. Prepared by JGL8/21/2009 LET US EXAMINE THE BONDING BETWEENMAGNESIUM AND FLUORINE87 88. FluorineMagnesium Prepared by JGLMetals Non- Noble Gases Group 88/21/2009 Group 1 to 13 are METALS Metals Neon 88 89. USING THE PERIODIC TABLE... Prepared by JGL 8/21/2009 Magnesium Flourine Group 2 Group 17 Period 3 Period 2 Metal Non-metal Forms cation Forms anion Z = 12 Z=9 Electron configuration Electron configuration (2,8,2) (2,7) Nearest noble gas Ne Nearest noble gas Ne Electron configuration of Electron configuration of Ne = (2,8)Ne = (2,8) 89 90. FORMATION OF IONIC BONDPrepared by JGL8/21/2009Cation formationAnion formation 2 electrons need to be1 electron needs to belost to go from (2,8,2) gained to go from (2,7)to (2,8)to (2,8)Mg Mg2+ + 2e- F + 1e- F-# of e- lost# of e- gained The Law of conservation of matter states that matter can neither created nor destroyed. Therefore # of e- lost HOW? # of e- gained90 91. THE ONLY WAY THIS CAN HAPPEN.Prepared by JGL8/21/2009 Is if ThenAnother Fluorine atom(F) accepts the 2ndelectronF + 1e- F- Mg Mg2+ + 2e- AndF + 1e- F-2 Fluorine ions are needed to bond to each Magnesium ion.91 92. IN TERMS OF IONIC EQUATIONS Prepared by JGL 8/21/2009 Cation equationAnion equationMg Mg2+ + 2e-F + 1e- F-F + 1e- F- 2F + 2e- 2F- 92 93. ADDING THE 2 EQUATIONSPrepared by JGL8/21/2009 Total ionic equation Ionic equationMg Mg2+ + 2e- Mg2+ + 2F- MgF2 2F + 2e- 2F-Mg + 2F Mg2+ + 2F-93 94. THEREFORE THE CHEMICAL FORMULAE Prepared by JGL 8/21/2009 FOR IONIC COMPOUND FORMED BETWEEN MAGNESIUM AND FLUORINE IS MGF2 A chemical formulae expresses the ratio ofatoms of elements within acompound. 94 95. IONIC BOND Prepared by JGLFORMATION PROCESS 8/21/2009CATION formationIONIC CompoundformationMg Mg2+ + 2e-Mg2+ + 2F- MgF2 ANION formationElectrostatic2F + 2e- 2F- attraction 95 96. IONIC BONDING EXERCISESPrepared by JGL8/21/2009 Demonstrate the type 1. Sodium and fluorineof bond formed 2. Magnesium andbetween the two setsoxygenof elements below in 3. Lithium and Sulphur 1.Diagrammatic form 2.Using atomic notation 3.Using ionic equations96 97. IONIC BONDING BETWEEN SODIUM now p= 11 and e-=10.There are AND FLUORINE protons, p=11 CATION FORMATIONcharge of +1 andThe number of Since each p has aSTEP 1:Prepared by JGLeach e- has a charge of -1, the overall8/21/2009 (because Z=11)charge becomes +11-10=+1. Using Bohr-Rutherford diagrams atomThe nearest noble gas to Na is therefore forms a positive ion Naneon, Ne. The atomic number for Ne1+ The number of or cation of monopositive charge +1is Z=10. Its electronic configuration neutrons, n=12 is therefore 2,8 (n = A Z)11 p- 1 e- 11 p+ 1 e- 12 n 12 nTo achieve this electronic Na atom has electronic configuration, Na must lose 1configuratione- of 2,8,1 because there are 2 e- in the 1st shell, 8 2,8,1 the 2nd shell and 1 e- ine- in2,8 Using atomic notation, the 3rd or outermost (valence) shell Now the electronic configurationbecomes 2,8 which is iso-electronicNaNa++1e -with Ne.Sodium has mass number A=23 and atomic number Z=11. 97 The atomic notation for sodium atom is therefore 2311Na. The number of electrons, e-=11 (because the number of protons is equal to the number of electrons in an atom) 98. There are now p= 9 and e-=10. I ONIC BONDING BETWEEN SODIUM ANDSince each p has a charge of +1 and FLUORINE TheTEP of ANION FORMATIONof -1, the overallSnumber 2:each e- has a charge Prepared by JGL protons, p=9 charge becomes +9-10=-1.Na atom therefore forms a negative ion or 8/21/2009 (because Z=9) Using Bohr-Rutherford diagramsof mono-negative charge -1anion The nearest noble gas to F is 1- The number of neon, Ne. The atomic number for Ne neutrons, n=10is Z=10. Its electronic configuration (n = A Z) is therefore 2,8 9p+ 1 e- 10 n9p10 nTo achieve this electronicconfiguration, F must gain 1 e-. F atom has electronic configuration of Law ofAccording to the2,82,7 conservation of matter, matter can 2,7 because there are 2 e- in the 1stNow the electronic configuration shell and 7 e- in the 2ndneither be created nor destroyed. Te Using atomic notation, or outermostelectron must therefore come 2,8 which is iso-electronicbecomes from- (valence) shellF + 1e -the Na atom.with Ne. F Fluorine has mass number A=19 and atomic number Z=9.98 The atomic notation for fluorine atom is therefore 199F. The number of electrons, e-=9 (because the number of protons is equal to the number of electrons in an atom) 99. IONIC BONDING BETWEEN SODIUM AND FLUORINE STEP 3: IONIC BOND FORMATION Prepared by JGL 8/21/2009 Using Bohr-Rutherford diagrams1+ 1- 11 p + 9p 10 n 12 n IONIC bond2,8 2,8Using atomic notation,Na+ + F- NaF The fluorine anion is attracted to the sodium cation as opposites attract. The electrostatic (electro meaning electrically or coming from electrons and static 99 meaning not moving) attraction between the anion and cation is the IONIC bond. 100. IN SUMMARY, FOR SODIUM AND FLUORINE Prepared by JGLNa Na++ 1 e-F+ 1 e- F- 8/21/2009 9p 10 n 11 p 12 n1- 1+9p 11 p 10 n 12 n 100 Na+ + F- NaF 101. SIMILARLY, FOR MAGNESIUM AND OXYGEN, Prepared by JGLMgMg2++ 2 e-O+ 2 e-O2- 8/21/2009 8p 8n 12 p 12 n1- 1+9p 11 p 10 n 12 n 101 Mg2+ + O2- MgO 102. SIMILARLY, FOR LITHIUM AND SULPHUR,Prepared by JGLLi Li+ + 1 e-S+ 2 e-S2-8/21/200916p16n 3p3p 4n4n 1-1+1+ 3p9p 3p10 n 4n4n 102 2Li++ S2-Li2S 103. Prepared by JGL 8/21/2009 REPRESENTING IONIC BONDING 103 Lewis structures (Dot and cross diagrams), chemical formulae, ionic equations, ionic notation 104. EXAMPLE: ALUMINIUM OXIDE Prepared by JGL 8/21/2009 CATION informationANION informationAluminium Oxygen SymbolAl Symbol O Group 3 Group 16 Period 3 Period 2 Metal Non-metal Forms cation Forms anion Z = 13 Z=8 Electron configuration (2,8,3) Electron configuration (2,6) Nearest noble gas Ne Nearest noble gas Ne Electron configuration of Ne = Electron configuration of Ne (2,8) = (2,8) Needs to lose 3 electrons to Needs to gain 2 electrons to achieve electron configuration of achieve electron 104 Neconfiguration of Ne 105. Prepared by JGL8/21/2009 HOW DO WE REPRESENT THIS INFORMATION MORESIMPLY?105 106. Prepared by JGL8/21/2009 An ionic equationexpresses what happens at an ionic level 106 107. CATION FORMATION: ALUMINIUMPrepared by JGL8/21/2009 In words: An aluminium atomloses three electrons to formaluminium cation 107 108. CATION FORMATION: ALUMINIUMPrepared by JGLAluminium atom is neutrallycharged. This is representedIonic equations must8/21/2009 Inby the element symbol ions in them Aluminium cation isionic equation form:have Al alone. represented by the element symbol and the charge on the ion. In this case it is 3+ Al Al3+ + 3 e - There is no =.Instead there is anRHS = Right handarrow. This means sideLHS =changes into. It os The RHS is electrically Left called an equationneutral because theHand because the LHS is number of electrons (3-) Side equivalent to RHS.cancels out the positive 108charge (3+) 109. The 3The charge iselectrons that represented bythe cations superscript. Forloses is CATION FORMATIONPrepared by JGLaluminium representedcation, it is 3+ here8/21/2009 Using Bohr-Rutherford diagrams 3+ 12 p 12 p 3 e- 12 n 12 nThe brackets indicate that this is part of aThe outermost orlarger entity. A cationvalence electrons are no usually has an anion tolonger on the outermost balance it off 109shellelectrically. 110. Prepared by JGL8/21/2009 ANOTHER WAY TO REPRESENT BONDING IS LEWIS (DOT AND CROSS) DIAGRAMS 110 111. WHAT ARE LEWIS (DOT AND CROSS) DIAGRAMS?Prepared by JGL8/21/2009 A Lewis structure is a simplified Bohr-Rutherford diagram Since chemical reactions take place among the valence and outermost electrons only Only these electrons are represented in the diagram. 111 112. COMPARISON OF BOHR-RUTHERFORD DIAGRAM TO LEWIS STRUCTUREPrepared by JGL8/21/2009 Bohr-Rutherford diagram Lewis structure Al atom Al atom13 p14 n AlThe 3 valence 112electrons arerepresented here. 113. COMPARISON OF BOHR-RUTHERFORD DIAGRAM TO LEWIS STRUCTURE Prepared by JGL 8/21/2009Bohr-Rutherford diagramLewis structure Al cationAl cation3+3+ 13 p 12 nAl No valenceelectrons arerepresented here all113have been lost toform cation. 114. FOR OXYGENPrepared by JGL8/21/2009Bohr-Rutherford diagram Lewis structure O anion O anionAll 8 valence 2- electrons are 2- represented here to form anion. 13 p12 n O 114 115. ACCORDING TO THE LAW OF CONSERVATION OF MATTER, MATTER CAN NEITHER BE CREATED NORPrepared by JGL DESTROYED.8/21/2009Since Al needs to give upAnd since O needs to gain 3e- only 2e- Al Al3+ + 3e- O + 2e- O2- There is a need to balance the number of e- onboth sides so that the Law is not violated!The only way to do this is to find the lowest common multiple for the number of electrons 115for the above. 116. EXCUSE ME?? WHAT IS THE LOWEST COMMON MULTIPLE? Prepared by JGL 8/21/2009 The Lowest Common Multiple (LCM) is the lowest number that is divisible among the members of a set of two or more numbers. For example, For a set of numbers (2,3,6), 6 is the LCM as 6 is the lowest number that can be divided by 2, 3 and 6 For a set of numbers (2,4,6), 12 is the LCM as 12 is the lowest number that can be divided by 2, 4 and 6 For a set of numbers (9,3,6), 18 is the LCM as 18 is the lowest number that can be divided by 9, 3 and 6116 117. SO FOR ALUMINIUM AND OXYGEN Prepared by JGL 8/21/2009 In order to balance this side, I would need to multiply by afactor/number that would give me the LCM.For this ionic half- For this ionic half-equation, the factor would equation, the factor would be 2 since be 3 since2 x 3e- = 6 e- 3 x 2e- = 6 e-Al Al3+ + 3e-O + 2e- O2- x2 2Al 2Al3+ + 6e- x3 3O + 6e- 3O2-The set of numbers in this case would be (3,2) The LCM would therefore be 6 as 6 is the lowest117 number that can be divided by both 2 and 3. 118. SO FOR ALUMINIUM AND OXYGEN Prepared by JGL 8/21/2009Since the number of electrons is balanced on both sides, the net effect is zero2Al 2Al3+ + 6e-+ 3O + 6e- 3O2- 2Al+ 3O 2Al3+ + 3O2- Since it requires 3 oxygen anions to bond with 2 aluminiumcations, the ratio of Al:O is 2:3.The chemical formulae is therefore Al2O3118 119. 2Al3+ + 3O2- USING BOHR-RUTHERFORD DIAGRAMSPrepared by JGL2-8/21/2009Al3+3+Al3+3+18p 8n 13 p 13 p 14 n 14 nO2- 2-2-8p 8p 8n 8n119 O2- O2- 120. USING LEWIS (DOT-AND-CROSS) DIAGRAMS Prepared by JGL2- 8/21/2009[Al] 3+O [Al] 3+ 2-2-O O 2Al3+ + 3O2-120 121. A SIMPLER METHOD FOR DETERMINING CHEMICALPrepared by JGL FORMULAE IS BY CROSSING CHARGES8/21/2009 To cross charges, 1. Write the symbol for first the cation and then theanion 2. Take the number of the charge of the anion andbring it to the bottom right hand corner of thecation. 3. Do the same for the cation. 4. If the charges are equal, then leave the formulaas a 1:1 ratio 5. If the charges are unequal but are both evennumbers then divide by the LCM. 6. If the charges are unequal but both are uneven 121numbers, then leave as is. 122. DETERMINING CHEMICAL FORMULA OF IONIC Prepared by JGL COMPOUNDS 8/21/2009 From the previous examples, when sodium and chlorine react: one sodium atom gives 1 electron to a chlorine atom. The loss of 1 electron transforms sodium atom into sodium cation The gain of 1 electron from sodium atom transforms chlorine atom into chlorine anion An ionic compound forms between sodium cations and chlorine cations The ratio of sodium ion to chlorine ions involved in 122 ion formation is 1:1 123. DETERMINING CHEMICAL FORMULAE OF IONICPrepared by JGL COMPOUNDS. EXAMPLE SODIUM CHLORIDE8/21/2009 Step 1: Form cation Na Na+ + 1e- Step 2: Form anion Cl + 1e- Cl- Step 3: Writechemical symbols for cation and anion Na 1+ + Cl1-Step 4: Crosscharges of anion and cation Na Cl123 124. IN CLASS EXERCISE Prepared by JGL 8/21/2009 Determine the chemical formulae of theAnswer following: Magnesium and sulphur MgS Potassium and nitrogen K3N Aluminum and chlorine AlCl3 Calcium and phosphorous Ca3P2 Sodium and oxygen Na2O Beryllium and Fluorine BeF2 Boron and nitrogen BN Magnesium and bromine MgBr2124 125. Prepared by JGL 8/21/2009 IONIC NOMENCLATURE 125 IUPAC naming rules for ionic compounds 126. (International Union of Pure and Applied Chemistry)IUPAC RULES FOR IONIC BONDINGPrepared by JGL8/21/2009 RULE #1: 1. The name of the metal comes first followed by the non-metal 2. Use lowercase letters throughoutRULE #2: The metals name remains unchangedRULE #3: 1. The non-metals name changes to end with suffix ide. 2. For oxygen, sulphur and nitrogen, remove ygen, ur andogen respectively and replace with ide 3. For all others, remove the last 3 letters and replace withide 4. It does not matter the number of non-metal ions in the 126compound they are not included in the name 127. (International Union of Pure and Applied Chemistry)IUPAC RULES FOR IONIC BONDINGPrepared by JGL8/21/2009 Using the first 3 rules stated in the previousslide, name the ionic compounds formed assumingthat the elements undergo ionic bonding 1. Oxygen, magnesium 2. Aluminum, nitrogenmagnesium oxide 3. Chlorine, sodium aluminum nitride 4. Fluorine, potassiumsodium chloride 5. Sulphur, calcium potassium fluoride calcium sulphide127 128. IUPAC RULES FOR IONIC BONDING Prepared by JGL 8/21/2009 RULE#4: For transition metals which can have more that one type ofcharge (oxidation state or valency), the valence numberof the metal must follow the name using romannumerals in brackets Name the ionic compounds formed given the followinginformation: 1. Sn+ , oxygen tin(I) oxide 2. Iodine, Pb+lead (I) iodide 3. Cu2+, chlorine copper (II) chloride 4. Fluorine, Ag+silver (I) fluoride 5. Mn7+, oxygen manganese (VII) oxide 6. Sulphur, Fe3+iron (III) sulphide128 129. Prepared by JGL 8/21/2009 COVALENT BONDING 129 Covalent bonding, polar covalent bonds, Lewis structures 130. Recall that Prepared by JGL Metals Non- 8/21/2009 Group 1 to 13 are METALSMetalsGroups 14 to18 are Non- MetalNon-metalmetals IoniccompoundPeriods 8 and 9 are METALS Metals 130 131. RECALL: NON-METALS Groups 14 to 18 are Non-metalsWhat happens Non-when elementsMetals that are non-metals want to 14 15 16 17 18combine? Atoms and The Periodic Table Prepared131by JGL3/30/2010 132. COVALENT BONDINGPrepared by JGL8/21/2009 If we look at group 14 elements , there are 4 valence electrons. The question arises what is the best way to achieve 8 valence electrons? Should 4 electrons be lost or gained? In this case, the choice to achieve a stable octet is by sharing electrons This is known as Definition: A covalent bond is a bond formed between 2 atoms in which a pair of electrons are shared so that both atoms can 132 achieve the electron configuration of the nearest noble gas. 133. COVALENT BONDINGPrepared by JGL8/21/2009 7 8 8 6 75 1 6 2 4 5 334What happens is that the electron shells overlap and the electrons are counted as if they belong to both nuclei. 133 134. EXAMPLE: CARBON AND OXYGENPrepared by JGL8/21/2009 Carbon informationOxygen informationCarbon Oxygen Symbol C Symbol O Group4 Group 16 Period 2 Period 2 Non-Metal Non-metal Z = 6 Electron configuration (2,4) Z=8 Nearest noble gas Ne Electron configuration (2,6) Electron configuration of Ne = Nearest noble gas Ne (2,8) Electron configuration of Ne Needs to share 4 electrons to= (2,8) achieve electron configuration of Needs to share 2 electrons to Neachieve electron134 configuration of Ne 135. USING BOHR-RUTHERFORD DIAGRAMSPrepared by JGL Oxygen requires 2 e-.Oxygen requires 2 e-.8/21/2009 It shares 2 e- with the carbon It shares 2 e- with the carbon atom. atom. 1 256 35 13 8p6p 8p 6n 8n 8n 24 46 C atom 78 8 7 O atomO atom However, carbon requires 4 e-.135 Even after it shares 2 e- with an oxygen atoms, it still requires 2 more e- in order to achieve its stable octet. It does so by sharing e- with another oxygen atom 136. USING BOHR-RUTHERFORD DIAGRAMS Prepared by JGL Because the ratio of C atoms to O atoms is 1:2 8/21/2009 the chemical formula is CO2 6p8p6n 8p8n 8n C atom O atomO atomThe covalent bonding is represented as shown above. 136Note that there are 4 covalent bonds because there are 4 pairs of shared electrons 137. USING LEWIS STRUTURESPrepared by JGL8/21/2009 The covalent O C Obonding is represented here137 138. USING LEWIS STRUTURESPrepared by JGL Instead of8/21/2009drawing theO C ONote that each represents adots and pair of electrons.crosses, acovalentbond can beOC Oshown using a 138 139. IN CLASS EXERCISE Prepared by JGL 8/21/2009 For the pairs of Sulphur and sulphur elements listed, draw Nitrogen and nitrogen the following: Oxygen and oxygen Bohr-Rutherford Hydrogen and hydrogen diagram showing Nitrogen and hydrogen bonding between elements Nitrogen and phosphorous Lewis structure showing bonding between elements Chemical formula139 140. SULPHUR AND SULPHURS S Prepared by JGL 8/21/2009 S S 16p 16 n 16p 16 n S2 140 141. NITROGEN AND NITROGENN N Prepared by JGL 8/21/2009 N N 7p 7n 7p 7n N2 141 142. OXYGEN AND OXYGENO OPrepared by JGL8/21/2009 O OO28p 8p 8n 8n 142 143. HYDROGEN AND HYDROGENPrepared by JGL8/21/2009 H H H H1p 1p0n 0nH2143 144. NITROGEN AND HYDROGEN HN HPrepared by JGL8/21/2009H 1p0n 7p 7n 1p 0n1pHN H 0nH NH3144 145. NITROGEN AND PHOSPHORUS Prepared by JGL 8/21/2009 PN 15p7p NP 16 n7nP N 145 146. Prepared by JGL 8/21/2009 DATIVE OR COORDINATE COVALENT BONDING 146 147. Sometimes one of the elements involved in the bonding will give up or share both of its electronsPrepared by JGL This type of covalent bond is called a8/21/2009 DATIVE OR COORDINATE COVALENT BOND This usually occurs withelements that have lone pairs of electrons147 148. WHAT IS A LONE PAIR OF ELECTRONS?Prepared by JGL8/21/2009 A pair of valenceelectrons that is not directly involved in bonding 148 149. HOW MANY LONE PAIRS DO THE FOLLOWING HAVE?Prepared by JGL8/21/2009 Atoms. Ions Oxygen Oxygen ion in Fluorine magnesium oxide Fluorine in sodium Nitrogen fluoride Phosphorous Nitrogen in calcium Aluminium nitride Sodium Phosphorous in sodium phosphide Aluminium in aluminium chloride149 150. Prepared by JGL SOLUTIONS3 28/21/200913 222O 31F 31N Lewis structure for Lewis structure for Lewis structure for oxygen atom fluorine atom nitrogen atom22 1 01P1AlNa Lewis structure for Lewis structure for 150 Lewis structure for Phosphorous atomfluorine atom sodium atom 151. SOLUTIONS This pair of 3 electrons is notPrepared by JGLincluded as they 2- involved in are2+8/21/2009 1 the ionic bond 2 O Mg3 This pair of electrons is not Lewis structure for magnesium oxide 3included as they 2- involved in are1+1the ionic bond2F Na 3 Lewis structure for 151sodium fluoride 152. SOLUTIONS This pair ofelectrons is notThis pair of4electrons is notPrepared by JGL included as theyThisare involved in2- isofpair 2- of as they included This are involved inpair8/21/2009electrons ionic bond4 1 the not electrons is not bond included as they the ionicincluded as theyNare involved in 2the ionic bond 3Nare involved in the ionic bond 2+2+ 2+Ca Ca Ca Lewis structure for calcium nitride 152 153. LET US LOOKPrepared by JGL8/21/2009 AT CARBONMONOXIDE 153 154. USING BOHR-RUTHERFORD DIAGRAMSPrepared by JGLOxygen requires 2 e-.8/21/2009 However, carbonIt shares 2 e- with the carbon atom. requires 4 e-.56Even after it shares 2 e- with an oxygen atoms, it still requires 2 1 more e- in order to38p 6p achieve its stable octet. 6n8n2 4 It does so by sharing a 7 lone pair of e- with the8 same oxygen atom i.e. oxygen forms a C atom dative bond with O atom carbon 154 155. Note that each represents CARBON MONOXIDECOPrepared by JGLa pair of electrons.8/21/2009 OC8p 6p8n 6nBecause there are three (3)covalent bonds, carbonOCmonoxide is said to have atriple bond 155 156. Prepared by JGL 8/21/2009 COVALENT NOMENCLATURE 156 157. IUPAC RULESPrepared by JGL8/21/2009 Rule 1: The more electronegative element (that is the element that is closest in atomic number to Fluorine) is written last. This element is given the suffix ide.Rule 2 When there is only one atom in the molecule, it remains as the element name157 158. IUPAC RULES 1 monoPrepared by JGL 2 di8/21/2009 Rule 3: When there is more that one atom for a given element in the molecule the 3 tri element is given the relevant prefix as follows:4 tetra 2 atoms di 3 atoms tri 5 penta 4 atoms tetra 6 hexa 5 atoms penta 6 atoms hexa7 hepta 7 atoms hepta 8 atoms octa 8 octa 9 atoms nona9 nona 10 atoms - deca 15810 deca 159. IN CLASS EXERCISEPrepared by JGL8/21/2009 Name the followingSolutions covalent compounds1. ICl7 Iodine heptachloride 2. N2O5 Dinitrogen pentaoxide 3. P2O3 Diphosphorous trioxide 4. SO2 Sulphur dioxide 5. SO3 Sulphur trioxide Nitrogen dichloride 6. NO2 Hydrogen chloride 7. HCl Hydrogen iodide 8. HI Tetraphosphorous 9. P4O10 decoxide 159 160. Prepared by JGL 8/21/2009 ATOMIC RADIUS 160 Concepts electron-shell shielding, electron-electron repulsion, effective nuclear charge 161. WHAT IS ATOMIC RADIUS?This is defined Nucleusas the half theNucleus distancePrepared by JGLbetween thenuclei of two8/21/2009atoms that arenot bound tothe samemolecule Why notmeasure theradius of a Atomic single atom?radiusBecause anatom is sosmall, it isEdge of really hard to Edge ofelectronmeasure a electron cloudsingle atom. 161cloud 162. FACTORS AFFECTING ATOMIC RADIUSPrepared by JGL8/21/2009NumberofelectronsNumberNumber of ofelectronprotons shells162 163. EXPLAINING INCREASING ATOMIC RADIUS Prepared by JGL 8/21/2009 LessMore MoreattractionLarger shielding ofelectron-High between Reduced electron valenceelectron number ofprotons of effective cloud i.e. (outermost) repulsionelectron nucleus nuclearLargerelectrons among shellsandchargeatomic by inner inner valence radiuselectronselectronselectrons.163 164. Prepared by JGL EXPLAINING DECREASING ATOMIC RADIUS8/21/2009 Higher Less Smaller attraction shielding ofelectron Increasedbetween valenceLow numbercloud i.e.effective protons of (outermost) of electron Smallernuclearnucleus and electrons by shells atomicchargevalenceinnerradius electrons.electrons 164 165. Atomic radius increasesATOMIC RADII IN PERIODIC TABLE down a group.Increasing number of shells and For every consecutivePrepared by JGL period, there is an increase Increasing atomic radiusin the number of electron8/21/2009 shells and inner electrons. inner electrons This means that there is increased shielding of valence electrons from nucleus by inner electrons.There is also increased electron-electron repulsion among inner electrons.This reduces the effective nuclear charge (that is the attraction between the positive nucleus and the valence electrons)Therefore , the atomic radius increases. Source: www.camsoft.co.kr/.../VFI_Atomic_Radii_sm.jpg165 166. Atomic radius decreases ATOMIC RADII IN PERIODIC TABLEacross a period For every consecutive Prepared by JGLelement within a givenperiod, there is an 8/21/2009increase in the number ofprotons and innerelectrons. Although the number of Decreasing atomic radius electrons is equivalent tlthe number of proton, thedistance between theelectron shell and thenucleus remains theIncreasing number of protons with same.same number of shells This means that there isdecreased shielding ofvalence electrons fromnucleus by innerelectrons. This results in a Source: www.camsoft.co.kr/.../VFI_Atomic_Radii_sm.jpgcontracting of the electroncloud,, resulting indecreasing atomic radius166 167. Prepared by JGL 8/21/2009 ELECTRONEGATIVITY 167 How atomic radius affects electronegativity 168. The moreprotons in theDEFINING ELECTRONEGATIVITYPrepared by JGL nucleus8/21/2009 Electronegativity is theThe smaller the atomic to ability of an atomradius attract electrons toAnd the fewer itself. electron shellsbetween the Dependent on atomicnucleus and radius and effective the valence nuclear charge (outermost)electrons Developed by Linus Pauling (Nobel Prize is the The effective nuclear chargeprotons ability to attract valence And the greater the winner(outermost) electrons) nucleus ability to attract electrons to itselfi.e. The higher the 168electronegativity 169. ATOMIC RADII AND ELECTRONEGATIVITYFluorine (F) has the smallest atomic radius and therefore thePrepared by JGLhighest electronegativity8/21/2009 Francium (Fr) has the largest atomic radius andtherefore the lowestelectronegativity 169Source: www.camsoft.co.kr/.../VFI_Atomic_Radii_sm.jpg 170. Prepared by JGLThe most 8/21/2009electronegativeelement isfluorine (F) electronegative is francium (Fr)Increasing The leastelectronegativity 170 171. Prepared by JGL 8/21/2009 INTERMOLECULAR AND INTRAMOLECULAR FORCES 171 Ionic bond, covalent bond, dipole-dipole interactions, ion-dipole, Wan der Waals, hydrogen bonding 172. DIFFERENCES BETWEENPrepared by JGL8/21/2009 INTRA-molecular forces INTER-molecular forces Intra means internal Inter means Think intra-venousbetween Think inter collegiate (IV) which means inside the veinwhich means betweencolleges Intramolecular forces Intermolecular forces are those bonds inside are those bonds the molecule orbetween one molecule compound or ion and another 172 173. TYPES OF Prepared by JGL 8/21/2009 INTRA-molecular forces INTER-molecular forces Covalent bonds Covalent bonds Ionic bonds Ionic bonds Van Der Waals Dipole-dipoleinteractions Hydrogen bonding Ion-dipole interactions173 174. INTERMOLECULAR FORCE AND STATES OF Prepared by JGLMATTER 8/21/2009 Solid LiquidFor a compound to exist For a compound to exist in the solid state at in the liquid state at room temperature androom temperature and pressure, pressure, the intermolecular the intermolecular forces must be fairly forces must be strong strong at the same time the at the same time the molecules/ions have molecules/ions have low kinetic energy. medium kinetic energy.174 175. COMPARATIVE STRENGTH OF INTERMOLECULAR Prepared by JGL FORCES 8/21/2009 Ionic Bond 300-600 kJ/mol Decreasing bond strength Covalent 200-400 kJ/mol Hydrogen Bonding 20-40 kJ/molIon-Dipole 10-20 kJ/mol Dipole-Dipole 1-5 kJ/mol Instantaneous Dipole/Induced Dipole 0.05-2 kJ/mol 175 176. Prepared by JGL 8/21/2009 VAN DER WAALS FORCES 176 Also known as London dispersion forces 177. VAN DER WAALS FORCESPrepared by JGL8/21/2009 Weakest of all One instantaneous dipole intermolecular forces. can induce another It is possible for two instantaneous dipole in an adjacent neutral molecules adjacent molecule (or to affect each other.atom). The nucleus of one The forces between molecule (or atom) attractsinstantaneous dipoles are the electrons of the called Van Der Waals adjacent molecule (orforces. atom). Polarizability is the ease For an instant, the electron with which an electron clouds become distorted. cloud can be deformed. In that instant a dipole is The larger the molecule formed (called an(the greater the number of instantaneous dipole). electrons) the morepolarizable177 178. VAN DER WAALS FORCESPrepared by JGL The other side This results in a slight dipole in is slightly more8/21/2009 the atom/molecule.negative inHowever, as electrons are incomparison. constant motion, this deipole is instantaneuos/As these electrons are drawn nearer to the adjacent atoms This makes this sidenucleus, the electrons of the atom moreThe protons from thisfrom the adjacentpositive than the next nucleus are attracted to 178atom are repelledsidethe electrons from theadjacent atom slightly 179. Source: http://universe-review.ca/I12-14-vanderwaals2.gif Prepared by JGL VAN DER WAALS FORCES 8/21/2009179 180. Atomic number increases down aAt RTP, Fluorine is a gas (F2(g)) Increasing density group. Prepared by JGL The mass of the atom mustAt RTP, Chlorine is a gas (Cl2(g)) therefore increase down a group. 8/21/2009 Van Der Waals forces must also increase down the group asthere are more temporary At RTP, Bromine is a liquid (Br2(l))electrostatic attractions becausethere are more electronsthe atoms are heavier and more At RTP, Iodine is a solid (I2(s))likely to come in contact with eachother180 181. Prepared by JGL 8/21/2009 DIPOLE-DIPOLE INTERACTIONS 181 182. WHAT IS A DIPOLE? A dipole- dipolePrepared by JGL8/21/2009 di = 2interaction is an Batteries have a positive pole and a electrostatic negative pole signified attraction and/or by a + sign and a - sign. repulsion This is an example of a between 2 dipole.dipoles within molecules 182 183. DIPOLE-DIPOLE INTERACTIONS Prepared by JGL 8/21/2009 Occur whenDipole-dipole interactions The elements within a molecule have very different electronegativities The atomic radii of the elements are small183 Source: http://www.chem.unsw.edu.au/coursenotes/CHEM1/nonunipass/ HainesIMF/images/dipoledipole.jpg 184. The greekThis means that the ClChlorine is closersymbol atoms side of the to fluorine than(pronounced Prepared by JGLmolecule is slightly more hydrogen is. It isdelta) meansnegative than the H therefore the moreslightly 8/21/2009 atoms side of the electronegative moleculeelement The attraction between the slightlypositive end of one molecule and the slightly negative end The pair of of an adjacentThis means that the H atoms side of theelectrons within the molecule is known ascovalent bond is a dipole-dipole molecule is morepositive than the Clmore attracted to interactionthe Cl atom then atoms side of the 184atom the H atom 185. Prepared by JGL 8/21/2009 HYDROGEN BONDING185 186. WHAT IS A HYDROGEN BOND?Prepared by JGL8/21/2009 This is an extreme form of dipole-dipole interactions It occurs in molecules where H atoms (hence the term hydrogen bond) are bonded to a very electronegative element (N, O and any of the halogens F, Cl, Br, I) 186 187. HOW IS A HYDROGEN BOND FORMED? Prepared by JGL The pair of e- in the covalent 8/21/2009 bond between H and O atom This accountsis drawn towards the more elctronegative element O for the high Let us use bond strength H only has 1 e-. of athis e- is drawnIf hydrogen water astowards the O bondonly 1 p is left. atom, asThis makes this sidean compared with of the molecule highly positive. other dipole- example dipole 187 interactions.Source:http://www.ccs.k12.in.us/chsBS/kons/kons/wonderful_world_of_files/image006.gif 188. Prepared by JGL 8/21/2009 ION-DIPOLE INTERACTIONS 188 Why ions dissolve in polar solvents 189. IONSWHAT ARE . Prepared by JGL 8/21/2009POLAR SOLVENTS This is a SOLVENT where the molecules of In every ionicthe solvent compound, there have a are dipole. negative ions(anions)andpositive ions 189(cations) 190. WHEN AN IONIC COMPOUND IS ADDED TO APOLAR SOLVENT.. Prepared by JGL Note that this is a physical and not a 8/21/2009 chemical change. The ions remain as ions and the molecules of the polar solvent have not changed. They are only separated a little more than previously.The molecules of the water However,salty This is why salttastes it requires polar solvent are salt is still there. It particles in because the many of theis just attracted to the ions to surround each ion a different physical state than before. to separate them andovercome the forces of190 attraction. 191. Prepared by JGL 8/21/2009 INTERMOLECULAR FORCE AND PHYSICAL PROPERTIES 191 How the type of intermolecular force within a compound determines that compounds physical properties 192. RECALL : COMPARATIVE STRENGTH OF Prepared by JGLINTERMOLECULAR FORCES 8/21/2009 Ionic Bond 300-600 kJ/mol Decreasing bond strength Covalent 200-400 kJ/mol Hydrogen Bonding 20-40 kJ/molIon-Dipole 10-20 kJ/mol Dipole-Dipole 1-5 kJ/mol Instantaneous Dipole/Induced Dipole 0.05-2 kJ/mol 192 193. THE STRONGER THE INTERMOLECULAR Prepared by JGL FORCE, THE MORE DENSE THAT STATE OF MATTER 8/21/2009 Type ofBondMost Examples intermolecular strengthlikely forces (kJ/mol)state ofmatter Van Der Waals0.05-2.00 Gas (g)Neon Ne(g) Oxygen O2(g) Nitrogen N2(g) Dipole-dipole1.00-5.00 Gas (g); Hydrogen chloride HCl (l) interactions Liquid (l) Hydrogen 20-40 Liquid (l) WaterH2O (l) bonding Covalent 200-400 SolidDiamondC(s)Ionic300-600 SolidSodium chloride NaCl(s)193 194. THE STRONGER THE INTERMOLECULARPrepared by JGL FORCE, THE HIGHER THE MELTING/BOILING POINT8/21/2009The higher Bond strength of the bond, point Type of intermolecularthe strength Most likely state of matterMelting theBoilingpoint/ greater the (kJ/mol) (in the form of heat forces energyenergy) required to separate theLow Van Der Waals 0.05-2.00 Gas (g)particles in a given physical state ofIncreasing bond strength Dipole-dipole 1.00-5.00 Gas (g); Liquid (l)Lowmatter. interactions Hydrogen20-40 Liquid (l) Medium bondingThis means that the temperatures at Covalent 200-400SolidVery highwhich solid turns to liquid (melting) and Ionic300-600SolidVery highliquid to gas (boiling) would be much 194higher. 195. Prepared by JGL 8/21/2009 PROPERTIES OF IONIC COMPOUNDS 195 196. IONIC COMPOUNDS . Prepared by JGL 8/21/2009 Are solid at room temperature and pressure (RTP) Have high melting and boiling points Have crystalline structures Conduct electricity in the molten state or aqueous state but not in the solid state Are soluble in polar solvents Are insoluble in organic or non-polar solvents196 197. REVIEW: STATES OF MATTER Prepared by JGL 8/21/2009 The state of matter of a Solids are denser than given substance is liquids dependent upon the Liquids are denser than energy of the particlesgases as well as the strength This is due to how of the attractionincreasingly stronger between the particles. the attraction between The stronger the the particles are as attraction, the closer state changes from gas the particles are andto liquid to solid the denser the state of matter 197 198. IONIC COMPOUNDS ARE SOLID ARE RTP Prepared by JGL 8/21/2009 The ionic bond is very strong. Every cation is ionically bonded to an anion and vice versa Please note that the overall ratio of ions remains the same The overall attraction between the millions of cations and anions creates a fairly denseThis is why and strong structure198 199. NEW CONCEPT LATENT HEATPrepared by JGL8/21/2009 To move from one state to the next, enough energy needs to be applied to the substance to increase the kinetic energy of the particles to overcome the forces of attraction to change state. The energy required to overcome these forces of attraction to finally allow the particles of a substance to fully transfer from one state to another is known as the LATENT HEAT. 199 200. IONIC COMPOUNDS HAVE HIGH MELTING AND Prepared by JGL BOILING POINTS 8/21/2009 Because the ionic bond is very strong. And the overall attraction between the millions of cations and anions creates a fairly dense and strong structure Quite a bit of energy is required to move from solid phase to liquid phase Ionic compounds therefore have high latent heats.This is why.200 201. IONIC COMPOUNDS HAVE CRYSTALLINEPrepared by JGLSTRUCTURESThis is why.8/21/2009 The ionic bond formed between cations and anions form an orderly regular pattern and fairly rigid angular structure This allows light to filter through andA crystal or crystalline solid is a solid be reflectedmaterial, whose constituent atoms,molecules, or ions are arranged in an 201orderly repeating pattern extending in allthree spatial dimensions. 202. IONIC COMPOUNDS DISSOLVE IN POLAR Prepared by JGL SOLVENTS 8/21/2009 This is why. Polar solvents areBecause the ionic compounds have those in which thenegative particles (anions) and positiveparticles have a particles (cations), they are attracted to slightly positive the polar solvents.and a slightly However, it requires many of the particlesnegative charge 202 at surround each ion to separate them and overcome the forces of attraction. 203. IONIC COMPOUNDS CONDUCT ELECTRICITY IN THE Prepared by JGL MOLTEN STATE AND AQUEOUS STATEThis is why. 8/21/2009 Once enough latent heat is applied to transform an ionic substance from the solid to liquid states (i.e. the substance melts), the ions are free to move This also applies when it is in the aqueous stateIf a positive pole (ANODE) is placed in the ionic liquid, the anions will be attracted to the anode. If a negative pole (CATHODE) is placed in the ionic liquid, the cations will be attracted to the cathode.203 The movement of the charged particles in a complete circuit allows molten or aqueous ionic compounds to conduct electricity 204. STRUCTURE OF SODIUM CHLORIDE (NACL) Prepared by JGL 8/21/2009 Sodium chloride (NaCl) or table salt has a 6:6 crystalline structure. This means that every Na+ is in contact with 6 Cl- and that every Cl- is in contact with 6 Na+.204 205. Prepared by JGL 8/21/2009 PROPERTIES OF COVALENT COMPOUNDS 205 206. COVALENT COMPOUNDS USUALLY. Prepared by JGL 8/21/2009 Are liquid or gases at room temperature and pressure (RTP) Have low melting and boiling points Have non-crystalline structures Do not conduct electricity either in the molten state or aqueous state Are insoluble in polar solvents Are soluble in organic or non-polar solvents206 207. REVIEW: STATES OF MATTER Prepared by JGL 8/21/2009 The state of matter of a Solids are denser than given substance is liquids dependent upon the Liquids are denser than energy of the particlesgases as well as the strength This is due to how of the attractionincreasingly stronger between the particles. the attraction between The stronger the the particles are as attraction, the closer state changes from gas the particles are andto liquid to solid the denser the state of matter 207 208. THE MAIN INTERMOLECULAR FORCES IN MANYPrepared by JGL COVALENT COMPOUNDS AREThis occurs when8/21/2009Dipole-Dipole interactionsmolecules are Van Der Waals (London dispersion)polar. The state ofmatter wouldmostly be liquid atRTP. This occurs when the molecules are non-Examples include:forces polar . The state of H2O(l) matter would mostly HCl(l)be gas at RTP.Examples include: Ne(g) O2(g) 208 N2(g) 209. A hexagonal ring of 6 carbon Each carbon is covalently bonded to 3 others. E Prepared by JGL atoms is XCEPTIONSTO THIS INCLUDE formed. 8/21/2009Each hexagonalGraphite is a solid at RTP Graphite ring is joined tobecauseform a sheet3 1 5 64 3 12 2Covalently bonded sheets of carbon atoms Graphite is made up of carbon increase atoms .Each sheet is loosely held density209 by weak Van der Waa;lsforces 210. A hexagonal ring of 6 carbon Each carbon is covalently bonded to 4 others. E Prepared by JGL atoms is XCEPTIONSTO THIS INCLUDE formed. 8/21/2009Each hexagonalGraphite is a solid at RTP Diamondring is joined tobecauseform a sheet11 4 2Covalentlybonded 3sheets ofcarbon atomsincrease Each sheet is loosely held density Diamond is made up of carbon210 atoms .by weak Van der Waa;lsforces 211. THE MAIN INTERMOLECULAR FORCES IN MANYPrepared by JGLCOVALENT COMPOUNDS ARE8/21/2009 Dipole-DipoleinteractionsVan Der Waals(London dispersion) forces This means that the melting points and boiling points 211 would be very low 212. EXCEPTIONS TO THIS INCLUDE Prepared by JGL 8/21/2009 Graphite Diamond212 213. THE MAIN INTERMOLECULAR FORCES IN MANY Prepared by JGL COVALENT COMPOUNDS ARE 8/21/2009Van Der WaalsDipole-Dipole (London dispersion) interactionsforcesA crystal or crystalline solid is a solid material, whose constituent atoms, molecules, or ions are arranged in an orderly repeating patternextending in all three spatial dimensionsVan Der Waals forces and dipole-dipole interactions are unstructured and fairly random. There is therefore no ordered arrangement of the molecules. Therefore most covalent compounds have no crystal213 structure. 214. Prepared by JGL 2148/21/2009 Graphite EXCEPTIONS TO THIS INCLUDE - GRAPHITE 215. EXCEPTIONS TO THIS INCLUDE Prepared by JGL 8/21/2009 Graphite Diamond215 216. COVALENT COMPOUNDS HAVE MOLECULES THAT ARE EITHERPrepared by JGL8/21/2009Polar Non-polar This means that there are no free electrons or free positively charged and/or free negatively charged particles to conductelectricity.Therefore most covalent compounds do not conduct 216electricity 217. There are no permanent dipoles to have electrostaticattractions with polar solvents Prepared by JGL In covalent compounds with non-Polar 8/21/2009polar molecules Therefore most covalent compounds areinsoluble in polar solvents217 218. In covalent compounds withThere arePolar polar moleculespermanent dipolesPrepared by JGL which have8/21/2009 electrostatic attractions withpolar solventsExamples include : 1. HX where X =F, Cl, Br or I 2. H2O (water) 3. NH3 (ammonia)Therefore covalent compounds with highly polar218molecules are soluble in polar solvents 219. Prepared by JGL 8/21/2009 METALLIC BONDING219 220. Prepared by JGL 8/21/2009 PROPERTIES OF METALLIC COMPOUNDS 220 221. Prepared by JGL 8/21/2009 ALLOTROPES221 222. Prepared by JGL 8/21/2009 THERMODYNAMICS OF ION FORMATION 222 Ionization energy, electron Affinity, Lattice energy 223. BUT WHY DO IONS FORM?Prepared by JGL8/21/2009 To understand why this Suppose you were very happens, we need tohungry, but you had to understand how energywalk to the end of the works. school to get lunch.Would you do it and why? Similarly, element Yes, because I can fill my s only bond or need (hunger) despite combine with the walk required. each other if thereWould you walk 10 miles ifyou did not have to? is a benefit in No.... terms of energy 223 224. FOR IONS TO FORM Prepared by JGL 8/21/2009 CATION ANION Electron(s) is/are Electron(s) is/are removed from valence added to valence electron shell.electron shell This requires ENERGY This releases ENERGY Bond formation only takes place when the reaction is energetically favourable.This usually means that there is energy released (denoted by a negative or minus(-) sign) at the end of the reaction.224 225. IONIZATION ENERGY AND ELECTRON AFFINITY Prepared by JGL 8/21/2009 Ionization energy (IE) Electron affinity (EA)This is defined as This is defined as The energy required to The energy released remove an electron when an electron is from an atom in itsadded to the valence or gaseous state from its outermost electron valence or outermost shell of an atom in its electron shell . gaseous state.For a given atom X,For a given atom X, X(g) + IE X+(g) + e- X(g) + e- X-(g) + EA225 226. LATTICE ENERGY Prepared by JGL 8/21/2009 This is defined asThe energy released when a cation and anion bond via an ionic bond is known as the LATTICE ENERGY (LE)For two ions, X+ and Y-, that combine to form an ionic solid XY X+(g) + Y-(g) XY(s) + LE 226 227. EXAMPLE: FORMATION OF SODIUM CHLORIDE Prepared by JGL 8/21/2009 To form sodium chlorideSodium loses one electron Na Na+ + 1 e-Chlorine gains one electron Cl + 1 e- Cl-An ionic bond forms between sodium and chlorine to form sodium chloride227 Na+ + Cl- NaCl 228. EXAMPLE: FORMATION OF SODIUM CHLORIDE - RELATED ENERGY CHANGESPrepared by JGL Na Na+ + 1 e-IE = + 495.8 kJ8/21/2009 Cl + 1 e- Cl-EA = - 352.4 kJIE + EA =+143.4 kJThis is not energetically favourable. However, the LE released compensates for this energyNa+ + Cl- NaCl LE = -787.3 kJTOTAL ENERGY= IE + EA + LE = +143.4 787.3 kJ 228 = -643.9 kJ 229. Prepared by JGL 8/21/2009 IONIZATION ENERGY 229 230. FACTORS AFFECTING IONIZATION ENERGY Prepared by JGL 8/21/2009 Ionization Energy (IE) is the energy required to remove an electron from an atom in its gaseous state. Therefore anything that makes it harder to remove an electron from the valence shell, will increase IE Conversely, anything that makes it easier to remove an electron from the valence shell, will decrease IE Therefore there is need to have a low or small IE to form a positive or cation.230 231. BASKETBALL AND If your opponent holds on Think if tightly to the ball, it will require more energy and you had toPrepared by JGL effort to take away the ball. take away8/21/2009 the ballSimilarly, the higherfrom IONIZATION ENERGYthe IE, the harder tosomeoneremove the valenceelectrons. during a basketball If he/she holds on loosely to the ball, it will be easier and game. require less energy to remove the ball from his/her hands. Similarly, the lower the IE, the easier it is toremove the ball. 231 232. WHAT FACTORS INCREASE IONIZATION ENERGY?Prepared by JGL8/21/2009Atomic radius Electro-Effective nuclearnegativityFactors chargeaffecting Ionization Energy Electron Number of configurationvalenceelectrons232 233. EFFECTIVE NUCLEAR CHARGE AND IONIZATION Prepared by JGL ENERGY The effective nuclear charge is the protons 8/21/2009ability to attract valenceAtomic radius(outermost) electrons) Electro-Effective nuclearnegativityFactors chargeaffecting IonizationThe greater the Energyeffective nuclearcharge, the moreclosely the Number ofvalence electrons Electron are held by the configurationvalenceelectronsnucleus and the233 higher the IE 234. Atomic radius is defined as the half APrepared by JGL the distanceTOMIC RADIUSAND IONIZATION ENERGY between the nuclei8/21/2009of two atoms thatare not bound to the same molecule Atomic radiusThe smaller the atomic radius, thecloser the valenceelectrons are toElectro-Effective the nucleus andnuclear the greater negativityFactors charge attraction between affectingthe two. It is wouldIonizationtherefore beEnergy harder to remove the valence electrons. ThisElectronNumber of increases IEconfigurationvalence electrons 234 235. ELECTRONEGATIVITY AND IONIZATION the Prepared by JGLThe higher ENERGYelectronegativity the greater 8/21/2009 Electronegativity is the attraction of the electrons the ability of an atom to the nucleus. This makes Atomic radius to attract electrons toremoval of electrons more itself.difficult and increases IEElectro-Effectivenuclear negativityFactors charge affectingIonizationEnergyElectronNumber ofconfigurationvalence electrons235 236. ELECTRONEGATIVITY AND IONIZATION ENERGY Prepared by JGL 8/21/2009 The closer the electron configuration initially to that ofAtomic radius the nearest noble gas, the more likely the ion will form and therefore the lower the IEElectronElectro-Effective nuclear configuration is thenegativityFactors charge arrangementaffecting of electrons in Ionization an atom, molecule orEnergy other body. Electron Number of configurationvalenceelectrons 236 237. ELECTRONEGATIVITY AND IONIZATION ENERGY Prepared by JGLThe more valence electrons, the 8/21/2009more electrons will be required to beremoved in order to get the electron Atomic radiusconfiguration of the nearest noblegas configuration.This means that it would requireElectro- Effective more energy to remove all thenuclear negativity Factors and therefore the IE would electrons charge increase. affecting The valence electrons areIonization the electrons in the Energy outermost shellElectron Number ofconfiguration valenceelectrons 237